C E R T A L E R T 

ADVISORY       CAUTIONARY      NON-DIRECTIVE

FOR INFORMATION, CONTACT AIRPORT SAFETY SPECIALIST, AAS-310 (202) 267.8729

DATE: 	December 12, 2002	No.  02-08	
TO: 	Airport Operators, Airline Operators,
FAA Airport Certification Safety Inspectors	
TOPIC: 	PAPI OPERATION	

This is to advise airport operators of the possibility of light signal interruption from PAPI units not operated continuously, e.g., those units activated through the use of pilot-controlled-lighting (PCL) systems.

Because external PAPI lenses, used to improve light signals, are exposed to ambient weather conditions, the possibility of dew and/or frost forming on the outside of the glass becomes a concern when the units are not operated continuously.  In particular, a PAPI unit operating in the “off” mode for an extended period of time during the evening hours could accumulate a level of environmental contaminants (e.g., dew or frost), which may not dissipate sufficiently to ensure correct light signals after pilot activation.

To preclude environmental contamination of PAPI lenses along with possible lighting signal interruption associated with limited dissipation of any dew/frost FAA recommends the following:

•	At airports where PAPI units are activated when needed and thus are not operated continuously, change airport lighting circuitry to ensure PAPI’s are preset to operate continuously on a low power setting, either 5 percent or 20 percent of full intensity as necessary for local site conditions.
•	Airport operators must submit changes as per the front cover of the Airport/Facility Directory removing the PAPI reference. 

OSB				      12/12/2002
Benedict D. Castellano
Airport Safety and Operations	Date